For example, Patent Document 1 (Japanese Patent Application Laid-Open Publication No. 11-272571) has proposed a method in which a command (for example, 8′h8C) representing a baud rate (for example, 76 kbps) of data is previously prepared and by using the baud rate based upon the command, data communication is carried out between the transmitting and receiving sides. On the transmitting side, in an attempt to set the baud rate to 76 kbps, the serial data 8′h8C is transmitted; and on the receiving side, by decoding and interpreting/recognizing this, the baud rate of its own is set to 76 kbps.
Moreover, Patent Document 2 (Japanese Patent Application Laid-Open Publication No. 2011-35473) has disclosed a baud rate error detection circuit that detects an abnormal waveform of a sync field in serial communication. First, the circuit generates an edge detection signal in response to an edge in the serial data, and based upon the edge detection signal, measures a bit width of a start bit so as to generate an expected value representing the measured bit width. Next, the width between edges after the start bit is successively measured so that, when an error from the expected value exceeds a permissible range, this state is determined as an abnormal state.